transition support for system state

The following commit defined two new values for the host state:
https://github.com/openbmc/phosphor-dbus-interfaces/commit/9f65dfeaa5ab22cae03db45c9916868da9864f83

These new state values, TransitioningToOff and TransitioningToRunning,
map quite well to the Redfish system PowerState values of PoweringOff
and PoweringOn.

There have been requests from external users of our Redfish interfaces
to know this level of detail, especially in the PoweringOff path due to
the length of time it can take (up to 2 hours is allowed for the host to
shut itself down gracefully).

Tested:
- Put host state D-Bus property in each of new states and verified
  Redfish API returned expected results.

Change-Id: I0c43dc2fa8b057beea48bc6f3dcde80d094ccfdb
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 137ab7e..57f6b96 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -648,6 +648,18 @@
                     aResp->res.jsonValue["PowerState"] = "On";
                     aResp->res.jsonValue["Status"]["State"] = "InTest";
                 }
+                else if (*s == "xyz.openbmc_project.State.Host.HostState."
+                               "TransitioningToRunning")
+                {
+                    aResp->res.jsonValue["PowerState"] = "PoweringOn";
+                    aResp->res.jsonValue["Status"]["State"] = "Disabled";
+                }
+                else if (*s == "xyz.openbmc_project.State.Host.HostState."
+                               "TransitioningToOff")
+                {
+                    aResp->res.jsonValue["PowerState"] = "PoweringOff";
+                    aResp->res.jsonValue["Status"]["State"] = "Disabled";
+                }
                 else
                 {
                     aResp->res.jsonValue["PowerState"] = "Off";